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An electronics rack comprising a first cage, a first heat sink positioned
at a rear and in thermal communication with the first cage, a second cage
positioned above the first cage, and a second heat sink in thermal
communication with the second cage. In another aspect, the present
invention provides an electronics rack comprising a frame, a cage, a heat
sink positioned at a rear of the frame, and a compliant thermal collector
operatively positioned between the cage and the heat sink. The compliant
thermal collector can comprise a heat pipe having a non-linear shape that
facilitates flexing of the heat pipe to change the length of the thermal
collector. The thermal collector advantageously includes a plurality of
heat pipes and a contact bar coupling the plurality of heat pipes.
Preferably, the rack further includes an adjusting mechanism (e.g.,
threaded rods) for adjusting a position of the contact bar.

[0002] This invention was made with government support under purchase
order number 7016038 awarded by Bechtel Marine Propulsion Corporation
(BMPC)--Knolls Atomic Power Laboratory (KAPL). The government has certain
rights in the invention.

Claims

1. An electronics rack comprising: a first cage adapted to support a
first electronic component, the first cage having a front and a rear; a
first heat sink positioned at a rear of the first cage and in thermal
communication with the first cage; a second cage adapted to support a
second electronic component and positioned above the first cage; and a
second heat sink separate from the first heat sink and in thermal
communication with the second cage.

2. The electronics rack of claim 1, wherein the first cage facilitates
insertion and removal of the first electronic component from the front.

3. The electronics rack of claim 1, wherein the first cage comprises a
plurality of first cages arranged in a vertical stack, and wherein the
first heat sink is in thermal communication with the plurality of first
cages.

4. The electronics rack of claim 1, where the second cage comprises a
cooling brick having a plurality of slots adapted to support upper edges
of a plurality of vertically-oriented electronic boards, and wherein the
cooling brick includes a transverse heat pipe positioned above the
plurality of slots.

5. The electronics rack of claim 1, wherein the second heat sink is
positioned above the second cage.

6. The electronics rack of claim 1, wherein the first heat sink is
substantially vertically-oriented and the second heat sink is
substantially horizontally-oriented.

7. An electronics rack comprising: a frame defining a front and a rear; a
cage adapted to support an electronic component, the cage being movable
between an open position toward the front and a closed position toward
the rear; a heat sink positioned at a rear of the frame; and a compliant
thermal collector operatively positioned between the cage and the heat
sink, the thermal collector being strained between the cage and the heat
sink when the cage is in the closed position to thereby provide thermal
communication between the cage and the heat sink when the cage is in the
closed position.

8. The electronics rack of claim 7, wherein the cage is mounted for
sliding movement relative to the frame.

9. The electronics rack of claim 7, wherein the cage facilitates
insertion and removal of the electronic component from the front.

10. The electronics rack of claim 7, wherein the cage comprises a
plurality of cages arranged in a vertical stack, and wherein the heat
sink is in thermal communication with the plurality of cages.

11. The electronics rack of claim 7, wherein the compliant thermal
collector comprises a heat pipe having a non-linear shape.

12. The electronics rack of claim 11, wherein the non-linear shape
includes a curved portion.

13. The electronics rack of claim 11, wherein the heat pipe has a length
and wherein the non-linear shape facilitates flexing of the heat pipe to
change the length.

14. The electronics rack of claim 7, wherein the thermal collector
includes a plurality of heat pipes and a contact bar coupling the
plurality of heat pipes, the contact bar being pressed into contact with
the heat sink.

15. The electronics rack of claim 14, further comprising an adjusting
mechanism for adjusting a position of the contact bar relative to the
heat sink.

[0001] This patent application claims priority to U.S. patent application
No. 62/299,336 filed on Feb. 24, 2016, the entire contents of which are
incorporated herein by reference.

BACKGROUND

[0003] In many electronic systems, the efficient cooling of electronic
components and other heat sources has become a significant problem. With
the advent of large-scale integrated circuit (IC) modules containing many
thousands of circuit elements, it has become possible to pack large
numbers of electronic components together within a very small volume.
These integrated circuit modules generate significant amounts of heat
during the course of their normal operation. Since most solid state
devices are sensitive to excessive temperatures, a solution to the
problem of the generation of heat by large scale IC's in close proximity
to one another has become of increasing concern in the industry.

[0004] Current heat transfer systems have proven to be inadequate for
removing the high levels of heat generated by heat sources at a low
enough thermal resistance and at a sufficiently fast rate. Thus, there
has developed a need to more efficiently remove heat from electronics
systems.

SUMMARY

[0005] In one aspect, the present invention provides an electronics rack
comprising a first cage adapted to support a first electronic component,
a first heat sink positioned at a rear of the first cage and in thermal
communication with the first cage (e.g., substantially
vertically-oriented behind the first cage), a second cage adapted to
support a second electronic component and positioned above the first
cage, and a second heat sink separate from the first heat sink and in
thermal communication with the second cage (e.g., substantially
horizontally-oriented above the second cage). Each cage preferably
facilitates insertion and removal of a plurality of electronic components
from the front. In one embodiment, the first cage comprises a plurality
of first cages arranged in a vertical stack, and the first heat sink is
in thermal communication with the plurality of first cages. The second
cage can comprise a cooling brick having a plurality of slots adapted to
support upper edges of a plurality of vertically-oriented electronic
boards, and the cooling brick can include a transverse heat pipe
positioned above the plurality of slots.

[0006] In another aspect, the present invention provides an electronics
rack comprising a frame defining a front and a rear, a cage adapted to
support an electronic component, a heat sink positioned at a rear of the
frame, and a compliant thermal collector operatively positioned between
the cage and the heat sink. The thermal collector is strained between the
cage and the heat sink when the cage is in a closed position to thereby
provide thermal communication between the cage and the heat sink when the
cage is in the closed position. In one embodiment, the compliant thermal
collector comprises a heat pipe having a non-linear shape (e.g.,
including a curved portion). The non-linear shape facilitates flexing of
the heat pipe to change the length of the thermal collector.

[0007] The thermal collector advantageously includes a plurality of heat
pipes and a contact bar coupling the plurality of heat pipes, wherein the
contact bar is pressed into contact with the heat sink. Preferably, the
rack further includes an adjusting mechanism (e.g., including a threaded
rod) for adjusting a position of the contact bar relative to the heat
sink.

[0008] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a perspective view of an electronics rack embodying the
present invention.

[0010] FIG. 2 is an enlarged perspective view of the electronics rack of
FIG. 1 showing a lower cage with a portion of the rack removed for
clarity.

[0011] FIG. 3 is the view of FIG. 2 with the lower cage slid to an open
position.

[0012] FIG. 4 is a partial side view of the electronics rack of FIG. 2.

[0013] FIG. 5 is an enlarged view of the circled portion of FIG. 4 and
showing an upper contact bar spaced from a rear heat sink.

[0014] FIG. 6 is the view of FIG. 5 with the upper contact bar moved into
contact with the rear heat sink.

[0015] FIG. 7 is a rear perspective view of the lower cage from the
electronics rack of FIGS. 1 and 2.

[0016] FIG. 8 is a bottom view of the lower cage of FIG. 7.

[0017] FIG. 9 is an enlarged front view of the cage of FIG. 2 showing a
PCB assembly positioned in the cage.

[0018] FIG. 10 is a partially exploded view of the PCB assembly from FIG.
9.

[0019] FIG. 11 is a section view of the assembled PCB assembly take at
line 11-11 in FIG. 9.

[0020] FIG. 12 is an enlarged front perspective view of an upper portion
of the electronics rack of FIG. 1 showing an upper cage with portions of
the electronics rack removed for clarity.

[0021] FIG. 13 is an exploded perspective view of a power supply assembly.

[0022] FIG. 14 is a perspective view of the upper cage.

[0023] FIG. 15 is a section view of an upper plate from the upper cage
taken along line 15-15 in FIG. 14.

[0024] FIG. 16 is a bottom perspective view of an upper heat sink.

[0025] FIG. 17 is a perspective view of a front face of the upper cage and
eccentric cams.

[0026] FIG. 18 is a section view of the power supply cage and eccentric
cams in a lowered position and taken along line 18-18 in FIG. 17.

[0027] FIG. 19 is the section view of FIG. 18 with the eccentric cams in a
raised position.

DETAILED DESCRIPTION

[0028] Before any embodiments of the invention are explained in detail, it
is to be understood that the invention is not limited in its application
to the details of construction and the arrangement of components set
forth in the following description or illustrated in the accompanying
drawings. The invention is capable of other embodiments and of being
practiced or of being carried out in various ways. Also, it is to be
understood that the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The use of
"including," "comprising" or "having" and variations thereof herein is
meant to encompass the items listed thereafter and equivalents thereof as
well as additional items. The terms "mounted," "connected" and "coupled"
are used broadly and encompass both direct and indirect mounting,
connecting and coupling. Further, "connected" and "coupled" are not
restricted to physical or mechanical connections or couplings, and can
include electrical connections or couplings, whether direct or indirect.

[0029] FIG. 1 illustrates an electronics cabinet 30 positioned on a base
32. The cabinet 30 includes a rack 34 and a door 36 hinged to the rack
34. The cabinet 30 is designed to receive multiple printed circuit board
(PCB) assemblies 38 and multiple power supply assemblies 40, as described
below in more detail.

[0030] The rack 34 includes a frame 42, a substantially horizontally
oriented upper heat sink 44 positioned above and supported by the frame
42, a substantially vertically oriented rear heat sink 46 positioned
behind the frame 42, and a plurality of lower and upper cages 48,50
slidable into and out of the frame 42. In the illustrated embodiment,
there are a total of four cages--three lower cages 48 and one upper cage
50. The three lower cages 48 in FIG. 1 are each adapted to support a
plurality of the PCB assemblies 38 (only one PCB assembly is shown in
each lower cage in FIG. 1), and the upper cage 50 in FIG. 1 is adapted to
support a plurality of power supply assemblies 40, as described below in
more detail.

[0031] Referring to FIGS. 2-8, each of the lower cages 48 includes a front
face 52, an upper thermal collector 54, a lower thermal collector 56, and
left and right side walls 58 to form a generally box-like arrangement.
This box-like arrangement is designed to slide into and out of the frame
42 on drawer slides 60 between a closed position (FIG. 2) and an open
position (FIG. 3). Handles 62 on the front face 52 facilitate opening the
lower cages 48.

[0032] Referring to FIGS. 4-8, the upper thermal collector 54 includes an
upper plate 64, upper heat pipes 66 partially embedded in the upper plate
64, and an upper contact bar 68 attached to distal ends of the upper heat
pipes 66. As best shown in FIGS. 7-8, each of the upper heat pipes 66 is
essentially identical to the others, and each includes a non-linear
portion 70 between the upper plate 64 and the upper contact bar 68. In
the illustrated embodiment, the non-linear portion 70 is curved to
facilitate flexing of the upper heat pipe 66 in order to change the
overall length of the upper thermal collector 54.

[0033] Similarly, the lower thermal collector 56 includes a lower plate
72, lower heat pipes 74 partially embedded in the lower plate 72, and a
lower contact bar 76 attached to the distal ends of the lower heat pipes
74. As with the upper heat pipes 66, each of the lower heat pipes 74 is
essentially identical to each other, and each includes a non-linear
portion 78 that is curved to facilitate flexing of the lower heat pipes
74 in order to allow a change in length of the lower thermal collector
56.

[0034] As used herein, a "heat pipe" refers to a closed system of heat
transfer in which a small amount of liquid within a sealed and evacuated
enclosure is cycled through an evaporation and condensation cycle, as is
known in the art. Heat entering the enclosure at one location on the
casing or "pipe" evaporates liquid at that location, producing vapor
which moves to a cooler location on the casing where it is condensed. The
movement of the vapor is motivated by a small vapor pressure differential
between the evaporator and the condenser locations. The heat transfer is
accomplished when the heat of vaporization, which produces the vapor, is
essentially moved with the vapor to the condenser location where it is
given up as the heat of condensation. In order for the heat transfer to
continue, the condensed liquid must be returned from the condenser to the
evaporator where it will again be vaporized. Although this return can be
accomplished by something as simple as gravity, capillary wicks have
generally been used to permit heat pipes to be independent of the effects
of gravity. Such a wick extends from a location near the condenser, where
the liquid originates, to a location at the evaporator where it is needed
for evaporation.

[0035] Referring to FIGS. 9-11, a series of cold rails 80 is positioned on
a lower surface of the upper plate 64 and on an upper surface of the
lower plate 72 to thereby define a series of elongated slots adapted to
receive the plurality of PCB assemblies 38. A resilient wedge lock 82
(FIG. 11) is positioned in each slot to secure each of the PCB assemblies
38 in the corresponding slots, as described below in more detail.

[0036] Each of the PCB assemblies 38 includes a printed circuit board 84,
a primary cold plate 86 and a secondary cold plate 88. As shown in FIGS.
9-11, the primary and secondary cold plates 86,88 sandwich the printed
circuit board 84 to facilitate heat transfer from the printed circuit
board 84 to the cold plates 86,88. Preferably, the cold plates 86,88 are
made from aluminum to enhance the rate of heat transfer. As shown in FIG.
11, each of the PCB assemblies 38 is inserted into a corresponding slot
in a lower cage 48 and is held in place by being sandwiched between the
corresponding wedge lock 82 and the corresponding cold rail 80.

[0037] Each of the lower cages further includes an upper adjuster and a
lower adjuster adapted to adjust the length of the upper and lower
thermal collectors 54,56, respectively. Referring to FIGS. 7-8, each of
the upper and lower adjusters includes five threaded rods 94 connected
between the front face 52 and the corresponding contact bar 68,76. The
proximate end 96 of each of the threaded rods 94 is keyed for rotation
relative to the front face 52. In addition, each proximate end 96 extends
slightly from the front face 52 and includes means to facilitate rotation
of the threaded rod 94, as shown in FIG. 4. In the illustrated
embodiment, the proximate end 96 of each threaded rod 94 is slotted to
facilitate insertion of a flathead screwdriver and rotation of the
threaded rod 94. The distal end 98 of each of the threaded rods 94 is
threaded into a corresponding threaded hole in the corresponding contact
bar 68,76. By rotating the threaded rods 94, the position of the
corresponding contact bar 68,76 relative to the rear heat sink 46 (and
relative to the front face 52) will be adjusted. In the illustrated
embodiment, this adjustment can be up to five millimeters of
displacement.

[0038] Referring to FIGS. 1-3, the rear heat sink 46 includes a rear plate
100 positioned at a rear of the rack 34 in a position where it can be
contacted by the contact bars 68,76 upon closing of the lower cages 48
(with appropriate adjustment of the upper and lower adjusters 90,92). The
rear heat sink 46 further includes rear heat pipes 102 embedded in the
rear plate 100 in order to distribute heat received from the contact bars
68,76 throughout a greater volume of the rear plate 100. The rear heat
sink 46 further includes rear fins 104 extending from a rear surface of
the rear plate 100 to facilitate passive dissipation of heat to the
surrounding air.

[0039] In operation, each of the lower cages 48 can be slid out of the
rack 34 to facilitate insertion and removal of PCB assemblies 38. After
all of the PCB assemblies 38 are properly installed in the corresponding
slots, the lower cage 48 can be slid back into the rack 34. However,
because of the variability and tolerances of the cabinet 30, it is
possible that the upper and lower contact bars 68,76 do not properly
engage the rear heat sink 46. Without solid engagement between the
contact bars 68,76 and the rear heat sink 46, heat dissipation from the
thermal collectors 54,56 to the rear heat sink 46 is substantially
compromised. In order to facilitate solid contact between the contact
bars 68,76 and the rear heat sink 46, the threaded rods 94 can be rotated
to move the contact bars 68,76 from a spaced position (FIG. 5) to a
contacting position (FIG. 6) relative to the rear heat sink 46.

[0040] Referring to FIG. 12, the upper cage 50 is designed to receive a
plurality of power supply assemblies 40 (only one power supply assembly
is shown in FIG. 12). The construction and arrangement of the upper cage
50 is slightly different from the lower cages 48 in that the upper cage
50 promotes heat transfer upward, while the lower cages 48 promote heat
transfer rearward. The illustrated upper cage 50 includes a front face
108, a top plate 110, a bottom plate 112, and left and right side walls
114 connecting the top and bottom plates 110,112 to form a generally
box-like arrangement. As with the lower cages 48, the upper cage 50
includes a series of top and bottom cold rails 116,118 (secured to the
top and bottom plates 110,112, respectively) that define slots for
receiving the power supply assemblies 40. However, in this arrangement,
the top cold rails 116 are different from the bottom cold rails 118.
Specifically, as shown in FIGS. 12, 14, and 15, the top cold rails 116
each include two embedded heat pipes 120 for distributing heat in each of
the top cold rails 116. In addition, the top plate 110 is different from
the bottom plate 112 in that the top plate 110 includes a plurality of
embedded heat pipes 122 positioned transverse to the orientation of the
top cold rails 116 (see FIGS. 14-15). These transverse heat pipes 122
transfer and distribute heat throughout the top plate 110. For
convenience, the combined assembly of the top plate 110 and the top cold
rails 116 is referred to as a "cooling brick," it being understood that a
cooling brick would not necessarily need to have those components.

[0041] As with the lower cages 48, the upper cage 50 includes wedge locks
124 (FIGS. 18-19) positioned in the slots to facilitate securing the
power supply assemblies 40 in the slots.

[0042] Similar to the PCB assemblies 38, the power supply assemblies 40
include a power supply board 126, a primary cold plate 128, and a
secondary cold plate 130 (see FIG. 13). The power supply board 126 is
sandwiched between the primary and secondary cold plates 128,130 to
facilitate the transfer of heat from the power supply board 126. Each
power supply assembly 40 is designed to be inserted into a pair of
opposed top and bottom slots (formed by the top and bottom cold rails
116,118, respectively) and held in place by being sandwiched between the
wedge locks 124 and the corresponding top and bottom cold rails 116,118,
as shown in FIGS. 18-19.

[0043] Referring to FIG. 13, each of the cold plates 86,88,128,130 can
further include heat pipes 132 embedded in the cold plate. In the
illustrated embodiment, these heat pipes 132 are only illustrated in
connection with the primary cold plate 128 of the power supply assembly.
These heat pipes 132 (shown in phantom in FIG. 13) can be positioned to
promote the transfer of heat in the desired direction. For example, when
used in the PCB assemblies 38 for the lower cages 48, the heat pipes 132
can be arranged to promote heat transfer upward and downward to the upper
and lower thermal collectors 54,56, respectively. When used in connection
with the power supply assembly 40, the heat pipes 132 can be embedded and
positioned to promote transfer of heat upward to the top plate 110 and
eventually to the upper heat sink 44.

[0044] Referring to FIG. 16, the upper heat sink 44 includes a
distribution plate 134 and a series of upper fins 136 extending upward
from the distribution plate 134. The distribution plate 134 is positioned
directly above the top plate 110 of the upper cage 50 and includes a
series of heat pipes 138 that distribute heat in the distribution plate
134. The illustrated heat pipes 138 are in multiple orientations, such as
parallel to the front face 108, perpendicular to the front face 108, and
oblique to the front face 108. The illustrated upper fins 136 are arrange
parallel to each other and perpendicular to the front face 108.

[0045] The upper cage 50 is designed to have a certain amount of vertical
play relative to the frame 42 and relative to the upper heat sink 44. For
example, in the illustrated embodiment, the upper cage 50 can be moved
vertically about five millimeters relative to the frame 42. This vertical
play allows the upper cage 50 to be moved vertically until the top plate
110 of the upper cage 50 contacts the distribution plate 134 of the upper
heat sink 44. Referring to FIG. 17, this vertical movement can be
accomplished using a series of eccentric cams 140 mounted to the frame 42
and positioned under and in contact with the upper cage 50. As best shown
in FIGS. 18-19, rotation of the eccentric cams 140 will cause the upper
cage 50 to move upwardly from a lowered position (FIG. 18) to a raised
position (FIG. 19) to thereby facilitate the creation of contact between
the top plate 110 and the distribution plate 134 of the upper heat sink
44. Each of the eccentric cams 140 includes a cam actuator 142 that
extends from a front surface of the frame 42 to facilitate rotation of
the eccentric cams 140. In the illustrated embodiment, the cam actuators
142 comprise hex heads that facilitate rotation of the eccentric cams 140
using a standard wrench.

[0046] Although the invention has been described in detail with reference
to certain preferred embodiments, variations and modifications exist
within the scope and spirit of one or more independent aspects of the
invention as described.